The present invention relates to cosmetic cleansing agents in the form of shaped soap products. Such agents are known per se. They are essentially surface-active substances or substance mixtures supplied to the consumer in various preparations. The invention relates in particular to bar soaps with improved smoothness and increased ability to disperse lime soap as a result of a content of talc and one or more cationic surfactants and the simultaneous absence of alkyl (oligo)glycosides.
Surface-active substancesxe2x80x94the most well-known being the alkali metal salts of higher fatty acids, i.e. the classical xe2x80x9csoapsxe2x80x9dxe2x80x94are amphiphilic substances which can emulsify the organic nonpolar substances in water.
These substances not only flush dirt from the skin and hair, they irritate skin and mucous membranes to a greater or lesser extent depending on the choice of surfactant or surfactant mixture. Although a large number of very mild surfactants is available, the surfactants of the prior art, however, are either mild, but cleanse poorly, or they cleanse well but irritate skin or mucous membranes.
Even simple bathing in water without the addition of surfactants will initially cause the horny layer of the skin to swell, the degree of this swelling depending, for example, on the bathing time and temperature. Water-soluble substances, e.g. water-soluble constituents of dirt, but also substances endogenous to the skin which are responsible for the water-binding capacity of the horny layer, are washed off or out at the same time. In addition, as a result of surface-active substances which are endogenous to the skin, skin fats are also dissolved and washed out to a certain extent. After the initial swelling, this causes a subsequent significant drying-out of the skin, which may be further intensified by washing-active additives.
The aim was therefore to remedy these shortcomings.
In healthy skin, these processes are generally of no consequence since the protective mechanisms of the skin can readily compensate for such slight disturbances to the upper layers of the skin. However, even in the case of nonpathological deviations from the norm, e.g. as a result of environmentally-induced wear damage or irritation, photodamage, aging skin etc., the protective mechanism of the surface of the skin is impaired. In some circumstances it is then no longer able to fulfill its role by itself and has to be regenerated by external measures. An object of the present invention was therefore to remedy this deficit of the prior art.
In body cleansing, a large role is played by bar soaps which are prepared nowadays on an industrial scale by continuous saponification of free fatty acids with alkalis, concentration of the base soap and spray drying. In this connection, a distinction is made between real alkali soaps, which comprise exclusively fatty acid salts and optionally also free fatty acids, and xe2x80x9cCombibarsxe2x80x9d, bar soaps which, in addition to fatty acid salts, also have further synthetic surfactants, usually fatty alcohol ether sulfates or fatty acid isethionates. In contrast, a special position is adopted by syndet bar soaps, xe2x80x9cSyndet barsxe2x80x9d which, apart from impurities, are free from fatty acid salts and comprise exclusively synthetic surfactants.
In Germany alone several million bar soaps are sold annually for body hygiene. Market requirements for these mass consumer articles are, however, becoming ever higher: bar soaps must not only cleanse the skin, but must also care for it, i.e. prevent drying-out, refat and offer protection against external influences. Naturally, it is expected that the soap is tolerated by the skin to a certain extent, but should nevertheless produce as large an amount of and as creamy a lather as possible during use and effect a pleasant feel on the skin. In this connection, manufacturers of bar soap are continually searching for new ingredients which take into account this increased profile of requirements.
A distinction is made between solid, mostly bar-shaped soaps, and liquid soaps. The main constituents are the alkali metal salts of the fatty acids of natural oils and fats, preferably of chain lengths C12-C18. Since lauric acid soaps lather particularly well, the lauric acid-rich coconut and palm kernel oils are preferred raw materials for the manufacture of fine soaps. The sodium salts of the fatty acid mixtures are solid, and the potassium salts are soft-pasty. For the saponification, the diluted sodium or potassium hydroxide solution is added to the fatty raw materials in a stoichiometric ratio such that an alkali excess of at most 0.05% is present in the finished soap. Nowadays, these soaps are often not manufactured directly from the fats, but from the fatty acids obtained by cleavage of fats.
Customary soap additives are fatty acids, fatty alcohols, lanolin, lecithin, vegetable oils, partial glycerides and other fat-like substances for the refatting of cleansed skin, antioxidants, such as ascorbyl palmitate or tocopherol for preventing autoxidation of the soap (rancidity), complexing agents, such as nitrilotriacetate, for the binding of heavy metal traces which could catalyze autoxidative deterioration, perfume oils for achieving the desired scent notes, dyes for coloring the soap bars and, if desired, special additives.
The most important types of fine soaps are:
toilet soaps containing 20-50% of coconut oil in the fatty mixture, up to 5% refatting fraction 0.5-2% of perfume oil, these make up the largest share of fine soaps;
luxury soaps containing up to 5% of particularly expensive perfume oils;
deodorant soaps containing additives of deodorizing active ingredient, such as, for example, 3,4,4xe2x80x2-trichlorocarbanilide (Triclocarban);
cream soaps with particularly high fractions of refatting substances which cream the skin.
baby soaps with good refatting and additionally care components, such as, for example, chamomile extracts, at most very weakly perfumed;
skin protection soaps with high proportions of refatting substances and further care and protecting additives, such as, for example, proteins;
transparent soaps with additives of glycerol, sugars etc., which prevent the crystallization of the fatty acid salts in the solidified soap melt and thus effect a transparent appearance;
floating soaps with a density of  less than 1, caused by small air bubbles incorporated in a controlled manner during the preparation.
soaps with abrasive additives for cleaning heavily soiled hands.
Upon washing with soap, a pH of 8-10 is established in the wash liquor. This alkalinity neutralizes the natural acid mantle of the skin (pH 5-6). Although in normal skin this acid mantle is reformed relatively quickly, in sensitive or predamaged skin irritations may result. A further disadvantage of soaps is the formation of insoluble lime soaps in hard water. These disadvantages are not present in the case of syndet soaps. These are based on synthetic anionic surfactants which can be incorporated with base substances, refatting agents and further additives to give soap-like bars. Their pH is variable within wide limits and in most cases is set to be neutral at pH 7 or adapted to the acid mantle of the skin at pH 5.5. They have excellent cleansing power, lather in every water hardness, even in sea water, the proportion of refatting additives has to be significantly higher than in normal soaps because of their intensive cleansing and degreasing action. Their disadvantage is the relatively high price.
Surfactants are amphiphilic substances which are able to dissolve organic nonpolar substances in water. As a result of their specific molecular structure having at least one hydrophilic and one hydrophobic molecular moiety, they are able to reduce the surface tension of water, wet skin, facilitate the removal and dissolution of dirt, facilitate rinsing andxe2x80x94if desired, control lathering.
The hydrophilic moieties of a surfactant molecule are mostly polar functional groups, for example xe2x80x94COOxe2x88x92, xe2x80x94OSO32xe2x88x92, xe2x80x94SO3xe2x88x92, while the hydrophobic moieties are generally nonpolar hydrocarbon radicals. Surfactants are generally classified according to the type and charge of the hydrophilic molecular moiety. In this connection, it is possible to differentiate between four groups:
anionic surfactants,
cationic surfactants,
amphoteric surfactants and
nonionic surfactants.
Anionic surfactants generally have carboxylate, sulfate or sulfonate groups as functional groups. In aqueous solution, they form negatively charged organic ions in an acidic or neutral medium. Cationic surfactants are almost exclusively characterized by the presence of a quaternary ammonium group. In aqueous solution, they form positively charged organic ions in an acidic or neutral medium. Amphoteric surfactants contain both anionic and cationic groups and behave accordingly in aqueous solution as anionic or cationic surfactants, depending on the pH. In a strongly acidic medium, they have a positive charge and in an alkaline medium they have a negative charge. By contrast, in the neutral pH range, they are zwitterionic, as the example below illustrates:
Typical nonionic surfactants are polyether chains. Nonionic surfactants do not form ions in an aqueous medium.
It is known that fine soaps based on tallow and coconut fatty acids can be changed and improved in terms of their application properties by numerous additives. Although current handbooks, e.g. Geoffrey Martin: The Modern Soap and Detergent Industry, Vol. 1, (1959), chapter VI, describe inorganic fillers as extenders for soaps, it is more likely in this connection that talc is associated with a disadvantageous effect in bar soap. The addition of 5-20% talc in combibars is described in DE 196 49 896. This addition is said to improve the smoothness and the ability to disperse lime soaps.